Hydrocarbon conversion



Patented June? 11, 1946 UNITED STATES PATENT OFFICE HYDBOCARBON CONVERSION HlllisO.

Folkins, Skokie,

and Carllsle- M.

Thacher, Highland Park, Ill., assignors to The Pure Oil Company, Chicago, 11L, acorporation of Ohio No Drawing. Application December 3, 1943,

Serial No. 512,780

3 Claims. .(Cl. 196-52) 10, 1943,"we have disclosed and claimed the process of cracking hydrocarbons in the presence of small amounts of organic compounds containing a bromine substituted aliphatic hydrocarbon group. In addition to the specific compounds therein disclosed, compounds such as benzyl bromide, in which bromineis substituted for hydrogen in an alkyl radical linked to an aromatic nucleus, fall within the broad class of compounds covered by the claims of that application.

We have now discovered-that bromine sub-. stituted cyclic compounds in which bromine is attached to one carbon in the cyclic nucleus, regardlessof the presence or absence of bromine in an alkyl side chain, are also very effective in accelerating thedecomposition of hydrocarbons when used in the amounts and under the conditions set forth in the aforesaid application,

Halogenated cyclic hydrocarbons which contain at least one bromine atom substituted in the ring such as brominated 'benzenes, brominated toiuenes, brominated xylenes, brominated naphthalenes, .lst ted anthracenes, bromochlorobenzenes, bromofiuorobenzenes, bromoiodobencases are particularly useful,

Examples of bromine-substituted cyclic com um which are useful as sensitizcrs in our process are:

Bromobenzene i-bromo-a-chlorobenzene l-bromo-4-chlcrobenzene i-bromo-i-fluorobenzcne l-bromo-z-iodobenzene l-bromo-3-iodobenzene l-bromo-i-iodcbcnzene 1,2-dibromobenzene LS-dibromobenzena l,4-dibromobenzene 1,2,3-tribromobenzene 1,2,4-tribromobenaene 1,3,5-tribromo l,2,4,5-tetrabromo 1,2,3,5-tetrabromobenzene Pentabromobenzene .Hexabromobenzene Bromotoluene (o, m and p) 4- bromo-m-xylene z-bromo-p-xylene 2 4,6-dibromo-m-xylenei-bromonaphthalene 2-bromonaphthalene 9-10-dibromoanthracene o-Bromo anisole p-Bromo anisole 1-bromo-2-nitrobenzene l-bromo-3-nitr0benzene 1-bromo-4-nitrobenzene 2,4,6-tribromophenol Bromocyclohexane 1,2,3,4,5,6-hexabromocyclohexane Bromocyclopentane Compounds containing more than one bromine stock before charging it to the heating and conversion zones, or it may be injected directly into the conversion zone. Brominated cyclic com pounds are eflective as crackingaccelerators or sensitizers in amounts as low as .1.% by weight of the charging stock. Amounts between ,1 and 5% by weight may be used eflectively, although larger amounts are useful. We prefer not to use amounts in excess of 3% by weight since amounts below 3% provide satisfactory acceleration of the cracking reaction without causing the presence of objectionable amounts of brominated compounds in the resulting product. Our experiments indicate that amounts of sensltizer, particularly where the sensitlzer is abrominated benzene ring compound, of 1% or less by weight will generally give satisfactory results.

Sensitizers in accordance with our invention are useful in conventional thermal cracking processes at either atmospheric, sub-atmospheric or super-atmospheric pressure. Cracking of hydrocarbon olls and gases may be carried out with brominated aromatics within the temperature range of approximately 650 F. to 2000" E, depending on the nature of the charging stock and the type of product desired. where cracking of hydrocarbon oils 'to gasoline is practiced, the temperature may range from approximately 650 to 1200 13'. when cracking gases or oils are cracked to aromatics. temperatures or approxi. mately 1000 to 1500" F. may be reso'rtedto.

- when it is desired to crack hydrocarbon'oiis or gases to butadiene, temperatures of the order of .1300 to 1600' F. may be used. Where cracking brominated aromatic compounds, in which brozone.

mine is linked to carbon in an aromatic ring, as cracking sensitizers, Pennsylvania gas oil was mixed with 0.5% by weight of p-dibromobenzene and cracked in a laboratory tube and drum cracking apparatus at temperatures of approximately 887 F. and 500 pounds per square inch pressure. The results obtained on the run using the p-dibromobenzene were compared with results obtained on similar runs, without any sensitizer and with p dichlorobenzene. The results. on three runs are given in the following table.

octane number to that produced without sensl- I tizer.

Although our invention is applicable to all known types of hydrocarbon cracking processes, both catalytic and purely thermal, it is particularly adapted for use in connection with purely thermal operations in which no solid catalyst is used. Our invention may be used in present types of thermal cracking processes without modifying 1 such processes or the apparatus in which they are conducted, except to the extent necessary to provide for the addition of the sensitizer to the charging stock at some point in the operation prior to the time the products leave the reaction It is to be understood that our invention is directed to the use of nuclear brominated isocyclic compounds generally, regardless whether groups or elements other than bromine are attached to the ring.

It is claimed:

1. Process for cracking hydrocarbons which comprises subjecting said hydrocarbons in the absence of solid catalysts to suitable cracking conditions of time, temperature and pressure in the Table Rate in Volume per Total gas Per cent gaL/hr. oi cent yield Gas g g g of analysis, Run of sensicharging Tam Pres- 100 F. Octane l 5 mole per cent N sensitizer tizer by stock and o sure per I. B. P., No. of

wt. gas oil from sq. inch 400 F. E. P. gasoline charge Pa. crude+ gasoline based V C; and C4 and Unsatu- H sensitizer on charge lighter heavier rates a 644 1.005 887 500 17. 6 56. 8 1.96 cu. ft., 0 cu. ft., 22. 9 5.1

69.97 g. 30.23 g. 649 p-Dibromo benzene 0.50 0.991 887 500 22. 8 58. 3 2.12 00.. (t., 0.38 cu. ft., 19.8 B. 5

72.23 g. 32.87 g. 650 p-Dichloro benzene 0. 0. 994 887 500 17. 3 49. 3 1.94 on. it., 0 37 cu. ft., 22. 8 5. 3

In each run the charging stock after admixture with the sensitizer, except in run 644 in which no.

sensitizer was used, was preheated in the heating coil t the desired reaction temperature and then charged to the reaction chamber, after which the reaction products were cooled and separated into liquid and gas fractions for analysis.

presence of a small quantity of p-dibromobenzene.

2. Process for cracking hydrocarbons containing 3 ormore carbon atoms in the molecule to 45 hydrocarbons containing less carbon atoms in the molecule which comprises subjecting said hydrocarbons to suitable conditions of time, temperature and pressure in the presence of a small amount of p-dibromo-benzene.

5o 3. The process of cracking hydrocarbon oil to gasoline boiling hydrocarbons which comprises subjecting said oil in the absence of solid catalysts to temperatures of approximately 650 to 1400 F. in the presence of from approximately 0.1 to 5% by weight of p-dibromo-benzene.

HILLIS O. FOLKINS. CARLISLE M. THACKER. 

